Fluval 305 or 405 for overstocked tank?

nettali

Hi Guys.. Just a quick question about selecting the best filter for a fish tank
40 Gal.
There are about 50x 5cm Goldfish in there.
I realise this is too many fish, but unfortunately i dont have the choice of decreasing the number as its not my tank.

What i want to do is the best i can to select a filter that will do the best job at making it as clean as possible.
The two options are the Fluval 305 and 405.
Base on the extra filtration the 405 seems the obvious choice, but would this be overkill for a 40gal tank? I've read the current may be too much.
Also, will the benefit from the 405 be enough to justify the extra space the filter will take up and the extra power usage? space is also an issue.
I guess what im asking is, will the 405 make a marked difference over the 305 that would justify taking the step up, considering the crowding of the tank.

Thanks

Lupin

I am very sorry to say this, nettali, but I will not agree to letting the number remain this way. I read this awhile ago and it took me awhile before I realize I am reading 50 Goldfish in a 40g. I keep Goldfish myself and to be honest, rather than seeing all of the fish stunted, they would be better off rehomed or euthanized if the option to rehome them, is not respected by your friend. I understand this is not your tank but all the same, one has to be responsible if he wants to enjoy his hobby. Would he enjoy a tank full of fish struggling to breathe for air? Would he enjoy the poop flying around? Would he enjoy his fish dying one by one because of several health issues brought by this ridiculously overcrowded condition?

Considering you have the same problem as many other Goldfish enthusiasts here did, I decided to trawl through my old posts and paste here important details that you need to know to save me time to work on your other issues.

Could you please tell us what strains are all these Goldfish? With fancy Goldfish, a general guideline would be 15g per fish. Pond types such as shubunkins, comets and common Goldfish require at least 20g per fish as these ones generally are feistier, larger and require more space to swim around. The fancy ones can reach at least 8-10 inches depending on the water conditions provided for them. I really suggest your friend should start planning a tank upgrade and sell the rest. How long did your friend keep all of those fish? For financial issues, Craiglist is your best bet for deals (assuming you're in US).

Do you have a test kit? Do you know the water parameters of your tank? If not, you really need a test kit particularly the liquid based ones by API due to their reliability and accuracy. Test strips are grossly inaccurate and should be avoided at all costs. You could invest in API liquid master test kit at $20-40 range. It will last you a year and it will give you assurance your water conditions are safe for the fish. This may help you as well discover that it may not just be constant harassment that cause their demise but whacked out water parameters. With seven small Goldfish, I am certain your water parameters would easily get out of safe range particularly elevated ammonia and nitrite.

Have you read about cycling yet? If not, I recommend reading this thread. Plenty of options and details are available there to help you know what cycling is all about.

Here's a chart of the nitrogen cycle obtained from another forum but it certainly helps give you a better understanding of what nitrogen cycle is.


Could you please tell us what your friend feed your fish and how often? How often does he change the water and how much? Even with a massive filtration without risking a whirlpool, none will ever resolve the issue of having 50 Goldfish in a 40g. Nothing will so your question asking for filtration (without reducing the number of fish) is pretty much moot, no matter the brand of filtration, the capacity, the water changes, etc.

SinCrisis

50??!! holy crap, do you have water left in there? or just fish? lol jk Anyway, when you say Goldfish, do you mean those feeders you see in petco that have like 200 fish in a 50 gallon tank? If so, i would just give a lot of them away to hobbyists that have predatory fish. However, if you have the more common bulbous Goldfish, theya re poop machiens and the numbers must be reduced by store returns. I am agaisnt euthanizing fish, as thats very... wrong, they all deserve to live IMO. Even if you got the msot powerful canister, with 50 Goldfish, you would still be cleaning it once every 2 days. Also the stress of overpopulation will certainly kill off a huge number of them, so it will be better to mvoe them now isntead of letting them all suffer. Moreover, this kind of overpopulation may spark diseases that could just decimate your tank.

If they are fancy Goldfish and there is really no way to reduce the numbers, then a new tank is another potential solution except it super expensive to do this... since you would need a tank the size of... a pond. Or if you must keep every fish and really MUST just get a filter then ur out of luck. I dont think anything short of a pond filter could handle that many fancy Goldfish.

Ultimatly your questions still need to be answered.
the 405 would create too powerful of a current in 40 gallons and your fish will be blown around. There areoutput diverters you can get as well as these tube things that will create multiple outputs so less pressure in one spot.

You do nt ahve the option of using the 305 since you have too many fish, actually even the 405 is not adaquate but if you must pick between these 2 the 405 is better and the extra filtration is justified becuase it puts the water through an extra set of baskets with media and will improve your biological filtration by a lot.

Yes the 405 is a way beter choice for your situation. However again, the "best" choice will be to reduce your population.

Lupin

Goldfish are the poorest choice for feeders yet. They contain too much fats and thiaminase that most predatory fish do not garner enough weight anymore and become nutrient deficient as a result of the thiaminase blocking the thiamin and other nutrients from being absorbed by the fish's body functions. See more information here pertaining towards use of Goldfish being totally moot.
HOLE IN THE HEAD + THIAMINASE - What you need to know!!!!!! - MonsterFishKeepers.com

Agree to disagree here. Your statement here proved contradictory to the statement quoted above.

Why is euthanasia necessary? Most fish that do not have any hopes of recovery once they suffer diseases that rarely will rectify themselves, often suffer a rather agonizing pain as they die. This is a rather subjective topic. This is what makes euthanasia necessary. With euthanasia, the fish is given a painless and quick death. That's the whole point of euthanasia. Fish themselves can feel pain than most people think. If they didn't struggle being eaten by a predator with a razor sharp teeth like the Hydrocynus goliath, they would simply roll their eyes and hang around limply as they are eaten alive, won't they?

On this issue, I should clarify that rather than seeing those Goldfish stunted and struggling to survive the poor conditions as a result of overcrowding, they would be better off euthanized if the owner refuses to change his plans. There are lots of things worse than death.

Nope. It will take more than every 2 days. It takes twice a day daily to change water without it turning cloudy quickly as a result of bacterial bloom, poop flying around, etc.

Even pond filters are not enough. They can only create whirlpool effect and still kill a majority of the fish.

SinCrisis

HAHA i know that its contradicting i personally dont use feeder fish. Im actualyl not a fan of using them but for a soltuion towards getting rid of them at least feeding them to amother fish will serve a purpose rather than just putting them to sleep with oril or sumthin...

The last comment about a pond filter was meant more as a joke since i doubt anyone would fit a pond filter onto a 40 gallon tank... The pressure from the output would porbably break the tank or damage the silicon seal...

sry if that last comment about a pond filter generated confusion or whatnot... i didnt think it would be taken seriously

Lupin

Using them as feeders is not an option. I clearly stated why not.

This is an issue when you are communicating online. It is hard to distinguish sarcasm and seriousness in your posts.